Top Secret Technology Demonstrator Aircraft Declassified - Known as technology demonstrators, these pioneering stealth aircraft remained top secret for years after their final flights before being declassified. Categorised as black projects and operating from the secret Groom Lake test site in Nevada, popularly known as Area 51, the three groundbreaking designs below tested low observable technologies and proved that stealth aircraft could operate deep behind enemy lines with a high degree of survivability. Together, they helped return the element of surprise to air warfare.From Nony